1. Field of Invention
The present invention relates to a method for manufacturing a micro-electromechanical structure.
2. Description of Related Art
Along with the progress of the process technology in semiconductor, the micro-electromechanical system (MEMS) has gained more and more attention. In the prior art, an active device circuit and the micro-electromechanical structure of the MEMS are independently and separately fabricated in different processes. After individually completing the active device circuit and the micro-electromechanical structure, these two parts are combined on a same substrate, and thus forming the MEMS. The above-mentioned method also refers to “System In Package” (SIP).
In another method, the micro-electromechanical structure and the active device circuit are integrated together. In particular, the process of forming the micro-electromechanical structure is performed after the semiconductor devices such as MOS and BJT devices are completed in the active device circuit. And then, a metallization process may be performed on the active device circuit to accomplish the MEMS at a wafer level. Sequentially, the wafer is cut and divided into chips, and followed by packaging each of the chips.
In the process of forming the micro-electromechanical structure, a plasma etching process such as reactive ion etching (RIE) may usually be adopted to form the moveable parts or constitution of the MEMS. However, the etching profile in the RIE process is not so good, and the equipment required for RIE is expensive. In addition, prior to packaging the chips, particles or contamination in the environment is possibly fallen into the micro-electromechanical structure, and thus destroying the desired function of the micro-electromechanical structure. Therefore, there exists in the art a new method of fabricating the micro-electromechanical structure that would resolve the above-mentioned problems.